In general if you're hearing sqeaking when you turn the wheels it means the steering system isn't getting enough fluid.
To locate the power steering reservoir, lean over the fan cowl (plastic cover behind radiator) and it's on your lower right (driver's side) just behind the coolant tank.
Check the power steering fluid level and the hose connections to the power steering pump.
If the connections are loose, tighten them. If they are tight then you should replace the hoses. This is the cheapest fix. If you still have a leak then connection bushings or the power steering pump itself may be leaking.
1996 E36 M44 318i 5sp LSD