That is my absolute favorite card trick of all time, and I first saw it being performed by David Blaine.
The main technique you need within this trick is the double lift. The trick involves utilizing it twice to transport the card at the spectator's hand with the one you're holding.
David Blaine Street Magic
He perform such magic tricks in streets you can learn and create your own audience.
It is so amazing that even if you get stuck doing the double elevator, and folks know that you're lifting two cards, they still cannot figure out how you did the trick.
Here is your tutorial and performance:
You just Learned hand sandwich card trick in this tutorial.
Today, David Blaine likes to make people pick a card prior to beginning the trick. This makes the trick look way cooler, but it looks just as cool if you just do it with any arbitrary cards. The principal result is in changing the card in their own hands.