Hi guys,
Can i coverage a space about 1600 meter with 3 or 4 Wireless AP like [cAP 2n or RB951Ui-2HnD] ? (i want to use WDS)

Yes. But many things play the role.

Yes. But many things play the role.

Thank you for your answer,
but can you explain more detail ?
"It is a hypermarket where there is no wall, there is just a lot of fluorescent lamps hanging from the ceiling and many shelf."

This is exactly what makes influence. Good thing is that there will be no interference as the hypermaket would be light metal construction, so no signals would come inside. At least I expect according to the hypermarkets I saw.
Bad is that shelves would be from metal too, as I asume.
It is not clear what effect do you expect from those four APs. You should descibe it more precisely. And you wrote nothing about the clients.

Due to the materials I'd say no. If you want to provide free internet to the shoppers I'd say no on density as well. A survey will give you your answers.

It's the question what he wants to achieve.