Hold a pistol in your hands, lay down with a wall on your left and your feet above you. In the example video I use a car to elevate my feet. Aim in with R2. Tap R1 to roll to the left and you'll see you start breaking through a bit. You must get your character to drop at the same time he rolls, and the game pushes you through the wall. Works on all objects except for cars with intact glass. To go through a car you have to break the glass.

Example Video