SQL Server 2012 :: Parsing XML That Does Not Quite Fit Normal XML Standards

I have an application that stores xml data in an unusal manor. Basically a SQL Key column and an XML string.The XML string is not really standard XML, but it is what it is, and I'm stuck with it. It is in the format;

<row key="Value.01" xml:space="preserve"><c1>FirstName</c1><c2>LastName</c2><c3>10 Street Address, City ST 012345-1234</c3><c4>5</c4><c5>50</c5><c6>500</c6></row>

I am able to pull values out via
SELECT
p.value('(./c1)[1]', 'VARCHAR(8000)') AS c1,
p.value('(./c2)[1]', 'VARCHAR(8000)') AS c2
FROM dbo.UserXMLTable
CROSS APPLY XMLRECORD.nodes('/row') t(p)
where p.value('(./c1)[1]', 'VARCHAR(8000)') like 'First%'

However I've been struggling with selecting row with a LIKE clause. Something like ;

SELECT *
FROM dbo.F_UserXMLTable
where XMLRECORD.value('(./c1)[1]', 'VARCHAR(8000)') like 'First%'

I have tried a number of permutations of XML syntax but so far have been stumpled.

Please note "<row key="Value.01" xml:space="preserve">" has a <SP> in the name 'row key' .