The conceptual framework of a research study is the system of concepts, assumptions, expectations, beliefs and theories that will support and inform the research. The conceptual framework may be a visual or a written product that would explain the main things to be studied, that is, the key factors, variables, and concepts and the presumed relationships among them. Hence, all these concepts, theories, etc should be considered in the literature review. Note however that the literature review should not be just about those you considered in the conceptual framework.
The most important thing to understand about conceptual framework is that it is primarily a conception or model of what is out there that one plans to study, and of what is going on with these things and why—a tentative theory of the phenomena that one is investigating. The function of this theory is to inform the rest of the research design—to help assess and refine goals, to develop realistic and relevant research questions and select appropriate methods and to identify potential validity threats to conclusion.
