Employer means any person engaged in commerce or in an industry or activity affecting commerce who employs 50 or more employees for each working day during each of 20 or more calendar workweeks in the current or preceding calendar year, and includes:

1. Any person who acts, directly or indirectly, in the interest of an employer to any of the employees of such employer;
2. Any successor in interest of an employer; and
3. Any public agency.