Can I use the Cheat! card to take an Item from another player, or use it to search through the discard pile to take an Item from it?

The Cheat! card allows you to equip an Item you normally couldn't due to Class/Race/slot/etc. restrictions. In other words, a second piece of Headgear, a second Big item (for non-Dwarves), an Item that requires a Hand or two when your other two are full, or the Bow With Ribbons for non-Elves.