I would take a pressure washer and clean off the motor as good as you can. If you don't have access to one you could go to a car wash just be carefull that you don't hit the electical or you may sit there for a bit till you can get it dry. This way you should only see anything new leaking and should be able to locate where it's comming from as well. Sounds like it could be leaking from the valve cover and going down the block to the headers.