Nematic liquid crystals, in particular the anisotropy of their physical properties and non-locality of their response to external excitation, present an attractive tool for guiding microscale dynamics of both living and artificial dynamic objects. The variety of orientational landscapes which can be encoded in liquid crystal director field (average molecular orientation) is dictated by the confining surfaces of the sample and external driving fields. In particular, we are interested in case when liquid crystal director field can self-assemble in complex patterns of topological defects in a reconfigurable manner under combined action of electric and magnetic fields. In this talk I will demonstrate how a simple combination of uniform electric field and an array of four permanent magnets can be used to generate distinct patterns of alternating topological defects in nematic director field.