The growth of the hadronic and nuclear scattering cross sections with energy is described by the linear BFKL evolution equation. At very high energies, when the parton density becomes high, the hadronic cross section reaches the unitarity limit, and the transition to high parton density is described by the non-linear BK and JIMWLK evolution equations. These equations are currently the starting point of discussion for future experiments like the proposed Electron Ion Collider (EIC) or the Large Hadron electron Collider (LHeC) and also play an important role in current RHIC and LHC experiments involving nucleus-nucleus and proton-nucleus collisions. Most of the current phenomenology of high-energy and high-density QCD is based on the leading-order evolution equations with only running coupling corrections. I will present a systematic procedure to include higher-order corrections into the BFKL/BK/JIMWLK evolution equations and the corresponding scattering cross sections using the high-energy Operator Product Expansion in terms of composite Wilson line operators.