Schematic: Jeeves

Schematic: Jeeves can be salvaged from any level 70-and-above mechanical mobs, such as the mechagnomes in Borean Tundra and Storm Peaks, the Stormforged Constructs in Halls of Lightning, and the Centrifuge Constructs in the Oculus.

Source
The best place to attempt to find it would be Ulduar, where it can be found on any of the mechanical elites, and also has a potential to drop from Flame Leviathan.

A popular place to farm this schematic is with the Library Guardians outside the Inventor's Library in The Storm Peaks. The Library Guardians also drop (to an engineer of at least skill 400) which launches the quest chain to learn how to make, an ingredient in making Jeeves.

Note that to get this schematic, you need to salvage the corpses, i.e. after the normal looting, you need to right-click the corpse again to pick up any engineering items.