Notwithstanding the provisions of section 56.330, the director of the department of revenue and administration of each county of the first class having a charter form of government and containing all or part of a city having a population of four hundred fifty thousand or more shall set aside the prosecuting attorney’s fees to be used as a contingent fund for the prosecuting attorney for the payment of the incidental expenses in bringing parties and witnesses from other states or countries and in properly preparing cases for trial, attending trial on changes of venue, attending at the taking of depositions, in printing briefs, and appearing before the appellate courts of the state, and generally the expenses he is put to in the proper and vigorous prosecution of the duties of his office. The fund shall be paid out as needed to the prosecuting attorney by the director of the department upon warrant of the prosecuting attorney approved and signed by a judge of the circuit court of said county.