The design of the 6G system will be based on a user-centric paradigm, enabling users to be involved in the creation and the management of network services and also providing them with a highly customized network experience. This paper proposes a realization of this paradigm by proposing a core network redesign from "Network Function-focus" to "User-focus" in conjunction with an AI-assisted approach that self-organises the network according to the user-requirements. A proof of concept implementation is presented based on both simulated and physical deployments, that demonstrate an optimal UPF placement taking into consideration user's preferences, proving the validity of the proposed approach.