There is an absolute distinction between designing something and working on it. Likewise, there is a difference between the substantial work and the finishing touches. When a project is deliberately left slightly unfinished, one of the reasons is to give the person finishing a great sense of satisfaction and achievement. Another reason is to enrich the relationship between the creator and the worker. It's not because the designer/builder lacked the ability to finish it himself.
A mistake that many adolescents make when they make their contribution is to, in their youthful enthusiasm, forget that they came in at the end of the process, not the beginning--they had no voice in the planning/design phase, nor did they participate in the substantive construction. Often, they'll decide that the rather mundane steps they're to follow are boring, too-easy and no-fun. Since, as many adolescents are 100% convinced 'they're smarter and more modern' than the "old school" designer, the original design is often discarded and the goal is never reached.
Tikkun Olam literally means repairing the world, and Kabbalistically refers to "partnering" with God to complete His world. This isn't because God is incapable, but rather He gives us a means to more closely approach/resemble Him. Furthermore, this is a specifically Jewish/Torah concept and it presupposes several basic understandings. First of these is that God totally transcends our potential abilities to fully grasp and understand Him in any way. This means we know only that infinitesimal slice of Him that He reveals to us. We don't know His motives, will or goals. Thus, even though we're invited to participate in completing/perfecting the created world, we don't know exactly what this "complete, perfect" world looks like. Another understanding is that we, the Jewish people, have a short but definite list of detailed instructions and that the rest of humanity has an even shorter, but equally detailed list of instructions. Humanity's instructions are the שבע מצות בני נח, Sheva Mitzvot B'nei Noah, the seven Noahide commandments (1), and the Jewish people have additional mitzvot adding up to תרי״ג (taryag), 613. (Since I'm not an authority on other religious traditions, I have no statement one way or another of the possible existence of additional mitzvot for other religions beyond that, if there are, they need to be consistent with the Noahide commandments all mankind (Jews included) are obligated to observe.)
There are many competing visions of an idealized world. But since we cannot describe God's ultimate goal, none of these can be 100% consistent with Tikkun Olam. Tikkun Olam might or might not have elements in common with what is today described as "Social Justice", but they are not the same. One is a secular political agenda which might have both desirable and undesirable features. Tikkun Olam is a Jewish religious concept which probably shares some, but not all, of Social Justice's features, but we just don't know. They are not identical. If Tikkun Olam can be said to have any "goal" whatsoever, it's to provide us a means for our relationship with God. It's a process, not a product.
All we know for sure about Tikkun Olam is our instruction list, which are the mitzvot: 7 (at least) for all of humanity and an additional 606 mandated for the Jewish people. We have never been granted a peek at the blueprint or of an "architect's model" of the finished product (what little we have been shown in the Torah (both written and oral) is intentionally vague, made up of poetic hints which aren't meant to be taken literally). Of course, Halacha, our sub-instructions to show us how to carry out our actual instructions (the mitzvot), has always (and still does) evolved to adjust to time and place (but that is a subject for at least several books). To emphasize again, Tikkun Olam is a very specific process; it is not a "product".
I would greatly prefer if instead of appropriating and distorting our sacred religious tradition, secular organizations and institutions who proclaim they're dedicated to "Tikkun Olam" would first find out what they're talking about. Of course, they're welcome to as many agendas as they wish, and I would love it if they would also promote mitzva observance as appropriate to their constituency, but all any of us, Jew and Gentile, can do to participate in Tikkun Olam is to perform those mitzvot relevant to us. Anything else is....well.....something else.
(1) Taken from Breslov.il (also discussed on many other websites) 1. Do not worship false gods. 2. Do not curse God. 3. Do not murder. 4. Do not be sexually immoral. 5. Do not steal. 6. Do not eat a limb removed from a live animal. 7. Set up courts and bring offenders to justice.