Whenever a body is taking a circular turn, it is being accelerated as it's angle is being changed constantly. At this point, inertia comes into play, or simply a force resisting the acceleration or the change in direction.
This inertial force is acting opposite to the direction of, the change in the direction of motion of the body. While friction, is acting aginst this inertial force, and hence friction is acting radially inwards.
This is the reason during rains, a car easily skids, in a direction opposite to the direction the body is trying to turn. As there is lower friction between the wheels of a car and the ground during rains.
Hope this helps.