Whenever in this code a license is required for the maintenance, operation or conduct of any business or establishment, or for doing business or engaging in any activity or occupation, any person, firm or corporation shall be subject to the requirement if, by himself or through an agent, employee or partner, he holds himself forth as being engaged in the business or occupation, or attempts to perform any part of such business or occupation in the city. (1977 Code § 5.04.020)