"Person served by the Department" or "Client" means any person who receives services or applies for services from the Department through its various offices. The term includes children for whom the Department is legally responsible, persons who involuntarily are investigated by the Department concerning allegations of child abuse or neglect and who may receive Department services during the course of, or subsequent to, such an investigation, persons who are receiving Department services through an order of the court, and persons who voluntarily request services from the Department. (R 431)