covering tiles to end up with floorboards

[retoucher]

hi everyone, i'm new here - and not too experienced - so please be kind
got a few queries, but i'll start from the basics

i've been asked to design a bar/pub kind of place, and it's all being done on a very low budget; we've got the location to be used, but before any of the decorating starts we have to overcome some tiles...
thing is, the owner doesn't want to remove them, just cover them up, so the idea I had was to put plywood over it and then screw some wood on top of that to give floorboards

so my question is, how do I attach the plywood to the tiles without completely ruining them? (so that everything could be taken off in the future and the tiles could still be used)
and what wood exactly would I use so that it would withstand the hundreds upon hundreds of people who'd walk over it in the future? would i put plywood/mdf/what over the tiles?

and the second part of the question is how would i attach some kind of mdf(?) to the walls, as the tiles go up approx 3/4 of it...

thanks for the help, and i apologize for my english as it's not my first language...

 

[retoucher]

oh just realized, wherever I said tiles i meant ceramic tiles