Not for Client, but as client is only visible on Project, it should not be an issue (in most cases, members should not see project screen, or only have readonly accees).
For Contact, indirectly yes, as Contacts list will be restricted to Contacts affected to the project....

Sorry, I dont' understand your answer.

When I assign Contacts and ressources to a project, all the user see always all the contacts in the "Contact menu".

What I try to do is to have a contact book with the useful informations and I would like that this Contact book could be view only by the contact/ressource assigned to a project

So, the question was not clear....

If you give access to Client and Contact screens, users will see all Clients and all Contacts.
This is because these screens are not Project dependant. So project restriction cannot be appied here.

That's too bad but ok, I understand. Thanks for your answer

I will try to find another way to propose a "Contact Book" to the participants of a project.

Perhaps have you an idea to do that ?

Nothing existing.
Something like a report ?