There is seldom such a thing as "incidental contact" between a runner (other than the BR) and a fielder. It is almost always either INT or OBS.
In this instance, as the contact occurs as a fielder is attempting to field a batted ball, R3 is guilty of runner INT. We leave it live to determine fair/foul: in this instance, it seems to have been a foul ball.
The result will depend on whether R3 had scored prior to the INT. If the INT happened first: R3 out, batter returns to the box with a strike added to his count unless he had 2 strikes (treat it as an ordinary foul ball). If R3 scored before the INT: the run counts, and the BR is out for his teammate's INT.