High transmission of electromagnetic (EM) waves is closely related to the reliability and stability of the indoor-to-outdoor wireless communication system. Due to the serious EM attenuation of the normal glasses under large incident angles, transparent film coatings that can be attached to the glasses have attracted extensive attention to maintain high EM transmissions in a wide angle range. In this paper, a wideband and wide-angle single-layered transparent metasurface is proposed to enhance the EM transmissions through the glasses. Detailed mechanisms, analytical models and elaborate numerical results are presented. As a proof-of-concept, a prototype of the metasurface based on Ag metal mesh is fabricated and tested. The measured results are in good agreement with the numerical simulations and calculations, thus validating the excellent EM performance. It is expected that the proposed single-layered metasurface with high transmittance in both microwave and light bands can find potential applications in the 5G and 6G communication scenarios.