Complex user's needs often require heterogeneous services to be combined together. In this paper, we explore a novel approach to enable flexible and dynamic composition of heterogeneous services for end users who are usually not familiar with technical process models. End-users are only required to model their goals and semantic reasoning is used for the composition itself. The possible service compositions are expressed in BPMN in order to be then processed by a BPMN engine. Since the composition is built on-the-fly, this approach avoids static linking of services and therefore is much more flexible.