Hey!
Give each enemy an attribute for accuracy. Check this attribute before each shot. If it succeeds, aim at the player, if it doesn't, aim at the player and adjust the angle for missing. It's not hard.
Another approach is having the attribute itself as the angle range. You just roll a random angle inthe range. The bigger the range, the worse will be the accuracy.
I prefer the first option, since it gives me more control. But both work.
Hope this helps. Cheers!