There is not a simple fix or definite answer. You will need to inspect the steering and front end/suspension components for looseness or wear. It may help to have a buddy wiggle the steering wheel (engine off) while you are under there looking for something loose. The reason to turn the wheel is to see if any of the steering components look loose, might try nudging the steering wheel with slight effort from left to right too. Also raise front tires off the ground and wiggle the front wheels and wiggle the wheel side to side ( 3 & 6 o'clock positions) and top to bottom (12 & 6 o'clock), this also helps having someone move the wheel while you are looking underneath. Most generally the side to side play would be something loose in the steering, top to bottom usually a wheel bearing. With tires still off the ground stick a long bar or prybar under the center of tire and pry up slightly and look at the ball joints.
All things need to be checked like, track bar brackets and bushings, all tie rods ends, drag link etc, ball joints, wheel bearings, control arm bushings. If everything looks good and tight with no play it might be the steering damper/shock or possibly out of balance and/or bad tire(s)