A free-space methodology specifically designed for characterizing inhomogeneous magneto-dielectric materials is presented. The associated modeling is performed with the finite-element method combined with the Born linearized approximation even if the dielectric constants of the materials are known to be large. Due to the introduction of a metallic element, a decoupling of the magnetic and dielectric effects is encountered. This enables us to recover the magnetic characteristic of the material from measured scattered fields, thanks to the inversion of the linear model. The entire methodology is described herein and assessed thanks to an experimental validation.