Customize Vector3 Inspector

I would want all the Vector3 had and horizontal view way into the inspector:

I was trying with this:

[CustomEditor(typeof(Vector3))]
public class Vector3Editor : Editor
{
	void OnInspectorGUI()
	{
	    target = EditorGUILayout.Vector3Field(target .name, target );
	    if (GUI.changed)
	        EditorUtility.SetDirty(target);
	}
}

But the compiler doesn’t let me to do it , Any idea?

CustomEditor works with components, i.e. MonoBehaviour scripts. Vector3 is not a MonoBehaviour.