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Magnetic frustration can arise in a square lattice of magnetic moments from competition between nearest-neighbor (J₁) and next-nearest-neighbor (J₂) exchange, with η = J₁/2J₂ governing the magnetic ground state. Remarkably, our inelastic neutron scattering (INS) measurements have shown that CaCo_1.86As₂ is a unique example of a metallic square-lattice system with nearly perfect frustration (|η| ≈ 1) despite possessing A-type antiferromagnetic (AF) order below a Néel temperature of T_N = 52 K. Our recent neutron diffraction data on Ca(Co_1-xFe_x)_2-yAs₂ show that the A-type AF order is suppressed past x = 0.12, and here we give results from INS experiments made at T = 6 K on single-crystal samples of x = 0.15. Instead of the walls of magnetic fluctuations found for x = 0, we rather find ferromagnetic-like fluctuations emerging from zone centers that, depending on the energy, is quickly suppressed with increasing momentum transfer. We discuss our results in terms of the changing degree of frustration with increasing x.