here's what I would do...

1. clean the shit out of the motor and entire engine bay using a strong degreaser. pressure wash if you can get your hands on one but if not some elbow grease and a scrubber brush will do it. pay extra attention to anywhere two surfaces mate to each other, valve cover to head, timing cover to engine, pan to block, etc.
2. after it's spotless dry it off with an air hose or sop up as much water as you can with some old towels and leave it to air dry. once dry proceed to step 3. don't forget to try not to spray any water directly into the sparkplug wells or onto the distributor (cover it with a bag if you're pressure washing).
3. start the engine and let the car idle, poke your head around the engine bay and look for the beginnings of a leak. let the car warm to operating temp while still looking around. blip the throttle a few times from under the hood and continue to look around. if nothing is found right away, see step 4.
4. if no leaks are found drive the car a short distance (maybe a mile or less), then stop and give it a look. again look everywhere you can, get a mechanic's inspection mirror beforehand if you want to be able to look down below the intake manifold and such without jacking up the car. after driving a little if you have a leak as serious as it sounds then you will notice oil originating from somewhere. if no leaks/smoke then drive some more until you find something. sometimes it's hard to pinpoint but if you take the time to clean it up and check then you'll find it for sure. if you get back from your testdrive and the thing is covered in oil anywhere go back to step 1 and start the process again, or just replace the car.