A new frictional contact model of an arbitrarily oriented substrate loaded by a rigid flat indenter is proposed in the present paper, in which a spatially varying friction coefficient is considered. With the aid of Fourier integral transformation, the governing equation is obtained and solved semi-analytically. The surface contact stress field, the moment applied to make the indenter move vertically to the substrate's top surface, as well as the nominal friction coefficient are investigated comprehensively. It is found that the contact behavior can be well improved by choosing proper friction coefficient, inhomogeneity parameter as well as gradient orientation angle. The new finding of the present paper should be helpful to access the surface wear resistance and design various inhomogeneous composites.