The distance between T3 and and T4 is not that far and every terminal is connected by sidewalk as they are all nex to each other. I like to compare it to a walk in an Atlanta concourse. Hopefully, you can have your luggage checked through so that you wont have to carry it with you. If you can walk with then just walk out the door and hang left going pas the international teminal. If it is alot of stuff you may have to take the shuttle van but it will be a very short ride. Here is a terminal map