can any person file criminal complaints against government servant.

Hello, thank you for your query.

You do not need prior permission to register a criminal complaint or an FIR case against a Government servant for an offense that he may have committed. 

However, if the offense is committed by a public servant to whom Section 197 of the CrPC is applicable, while acting or purporting to act in the discharge of his official duty, previous sanction of the concerned Government may be necessary before the Court takes cognizance of such offense. 

similarly, if the offense by the public servant is under the provisions of the Prevention of Corruption Act, 1988, previous sanction of the competent authority may be needed before the Court takes cognizance of such offense.

Hope this solves your query.

What are the facts? What is the context?

The query lacks clarity as to whether the offense is related to his job or outside the job, personal.  The complainant has to make a complaint to the police and it is left to the investigating officer to follow the laid down procedure depending on such type of offense.