[[!migxLoopCollection?
&packageName=`gallery`
&classname=`Gallery`
&sortConfig=`[{"sortby":"title","sortdir":"ASC"}]`
&where=`{"image_names:LIKE":"%John%","published":"1"}`
&tpl=`mGalleryAlbum`
]]
&where=`{"image_names:LIKE":"%John% or %Tom%","published":"1"}`
This question has been answered by just_nico. See the first response.
&where=`[
{"image_names:LIKE":"%John%"},
{"OR:image_names:LIKE":"%Tom%"},
{"published":"1"}
]`