These engines leak from everywhere like most '90+ BMW designs. The passenger side has most of the plumbing - hoses, gaskets etc, lots of things to leak on that side. Oil filter housing gasket usually creates the biggest leak, then you got vanos lines, crankcase vent hoses, power steering hoses which drip from above, things like the sump gasket, crankshaft seal, dipstick o-ring are usually leaking somewhat at this age unless someone has replaced them.
Best bet is the take off the cover off, go under the car and de grease\clean the entire area. Check back after some driving to get an idea of what leaking (which will probably be many things as most people don't bother to fix them)
The entire subframe\suspension is alloy on these cars