By half pushups I don't mean bending knees, I mean i can't touch the ground fully, there is always some space left between my chest and ground(on many forums they tell that pushups are only good when you can do them in full range of motion)I tried incline pushups but they seem to only work my upper chest.
Half reps, half the results.
The bottom portion of a pushup is the most chest-intensive part of the range of motion. The upper portion, which you're doing, is mostly triceps. So when you ask "are half pushups any good?", the answer is "yes, but not as good as whole pushups".
You have to weigh this against what you want to accomplish. If you want to build a bigger and stronger chest, the top half of the pushup isn't going to do much for you.
You don't mention why you can't do the bottom part of the movement, but I would suggest that you work on getting there, unless you have an illness or injury that prevents it. Pushups, and all their variations, are an excellent chest builder.