Updates a contact's name, client ID, tags, and its primary or secondary email, phone and address. Only the fields sent with a value change: blank or missing fields are left as they are, tags are added to the existing ones, and nothing is deleted. A primary* value replaces the contact's primary email, phone or address; a secondary* value replaces its oldest non-primary one. Either is added when the contact has none. Changing the primary email also changes the client portal login.