"Wie geht's?" in German

Incorrect. "Wie geht's" is directly translated to "How goings?" or in meaning "How's it going?" ... or
" 'Sup?" ... all of which are a sort of slang for saying "How are you/what's happening".
Que-ce que tu fais, AFAIK, is a more literal question, such as "Bobby, what the hell are you doing?" or "What is it that you are doing there?"