Drawing the human face in a front view and trying to turn it in a way to make it a side view would be kind of difficult to achieve without erasing and mostly starting over. Because the human face shape changes when the face is turned away. Such as the direction of the nose, and overall shape of the face.
Example below are faces in different angles: pointed up, down, 3/4, and profile. By looking at these images you are able to tell how different the face structure changes when the head is turned. It will give some ideas of how to draw a character in a 3/4 view.
Studying the anatomy of the human face, the bone structure, the muscle structure would be a good benefit.
Took your image, and tried to draw it in a similar style related to the original front facing drawing. (Drawing with mouse so, I apologize) The face is going to have to turn and adjust so that the right side(our viewing side) will be the farthest away from the viewer. To make it look like the person face is turned.