Posibility:
1. The tie rod universal joint/ball joint worn out. Need to replace the tie rod end
How to check:
Jack up the front tyre. Hold tyre at left and right and push it left and right. If there's any movement, conform the tie rod
2. The rubber bushing at the steering column karput/koyak (if there is any. E30 got but other model i'm not to sure). need to be replaced
How to check:
Push in you key so that the steering wheel are free. Rotate it left and right and see whether the upper part of the steering column move but the lower part didn't move. if this happened, it's karput
3. Worst scenario your steering rack housing (internal part) worn out. Need replacement.
Hoist up the car. Loosen out the cover right under the steering column where it joint the steering rack. Inside you can see another nut. Get somebody to steer the steering left and right and see if the nut going up and down. If this happened, most probably the housing where it hold the steering pinion bearing already worn out.
That's all i know. Hope it help.