I honestly can't believe your friend is German or maybe he is joking. I promise you that sentence is very wrong.
First, the comma is wrong.
Secondly, the case.
Thirdly, I can't say 100% why but semantically it's also off.
Grammatically correct would be "Hast du gefunden, wo dein Platz ist?" but even the grammatically correct version sounds very off to me. It would make more sense to say "Hast du herausgefunden, wo dein Platz ist?" or as stated before "Hast du deinen Platz gefunden?"
You can't use "finden" (to find) and "wo" (where) together as a relation. You can only find people/animals, objects or places but you can't find "where something is".
Another possible correction would be "Hast du den Ort gefunden, wo (an dem) dein Platz ist?". This sounds kinda double but it shows what works and what doesn't. As soon as you put a word you can "find" (people, animals, objects, places) that sentence construction works.
I tried it with other words. "Hast du gefunden, wo das Haus ist?" "Hast du gefunden, wo dein Lehrer ist?" "Hast du gefunden, wo sein Hund ist?"
I can conclude that is definitely not possible in Standard German. Maybe it would be in some dialect or colloquial in a certain region.
Sorry for the long and probably confusing answer. I don't know 100% how to explain why it doesn't work but I'm sure it doesn't (at least in standard German)