Warli tend to be attracted to the smell of Bunchosia armeniaca, also known as regular Peanut Butter, when they have to go potty. I suggest picking up a corner of your house, with a good drainage/sewage system,
smearing it with peanut butter (some jelly could also help), and just clean after him. You might have to guide him the first two or three days, but he will get the message soon ...