The sentence is a little bit strange without context but I will anwser to you. J'ai tout prêt = All is ready for me (for example "all my stuff is ready) but maybe the correct grammar would be "J'ai tout de près" Près de moi = Close to me. So at the end we can understand that sentence differently with the context. Maybe that person want to say he had everything needed around him. Or maybe he is ready to do something and he prepared all what he needed and he have that close to him. If you still don't understand everything, send me a private message.

The global sense is that he already have what he needs on him . Like the question what will you pick with you on a desert I've island ? All I have on me because I got all I need on me . I suppose that was the sense

Le sens de cette phrase n'est pas claire !