2004 Chrysler Pacifica What could it be

It over heated I had the radiator replaced.I still have to put water in every 3 days, I don't see where the water is leaking from A week later the oil light comes on I put oil in the light never goes bn off. I let it sit for a whole day, I check under the hood and notice the oil is coming back through the oil cap onto the left side of engine amd onto the fans