Newcastle United have made four additions so far this summer transfer window and they’re now desperate to sign a defender. Newcastle are in talks to sign Crystal Palace’s Marc Guehi but that deal is yet to progress due to his lofty price tag. As such, the Magpies are looking at alternative targets just in case they fail to agree a deal with Palace and it’s just come to light that they’ve made contact with a defender’s agent on the continent. READ MORE: Rival club owner issues Newcastle United takeover claim as £125m plan revealedNewcastle United contact Logan Costa’s agent TBR reported earlier…