Goal-Oriented dialogue systems help users accomplish various tasks, for instance book a flight ticket or make a restaurant reservation, etc. In order to complete the tasks, these assistants provide a conversational interface to multiple third-party services/APIs. Dialogue State Tracking (DST) is a core component of such systems. After every user utterance, it outputs the dialogue state which is essentially a summary of the conversation till the current run. With ever-increasing number of services and constantly changing ontologies, existing approaches fall short as they often rely on a single static ontology to work with. In this work, we focus on a specific condition, in which 1) a guided schema is provided, 2) target slot value can be found as word segments in the dialogue context.