<audit>
  <table name="client" pkValue ="4402">
    <ID>
      <old>4402</old>
      <new>4402</new>
    </ID>
    <firstname>
      <old>FraNs</old>
      <new>Frans</new>
    </firstname>
    <surname>
      <old>coetzee</old>
      <new>Coetzee</new>
    </surname>
  </table>
</audit>

create table #clientOLD(ID int, firstname varchar(50), surname varchar(50))
create table #clientNew(ID int, firstname varchar(50), surname varchar(50))

insert into #clientOLD
select 4402, 'FraNs', 'coetzee'

insert into #clientNew
select 4402, 'Frans', 'Coetzee'

select 'client' as [name], ID as 'pkValue',* 
  from 
	(select 'OLD' as value,* from #clientOLD 
	union all
	select 'NEW' as value,* from #clientNew) tmp 
order by tmp.id, tmp.value
for xml raw('table'), root('AUDIT'), type    	


--drop table #clientOLD, #clientNew

select
	'client',
	a.ID,
	'OLD',
	'NEW',
	a.firstname,
	b.firstname,
	a.surname,
	b.surname
from
	#clientOLD a
	inner join #clientNew b on b.id = a.id

select
	'client' as [@name],
	a.ID as '@pkValue',
	'OLD' as [ID/old],
	'NEW' as [ID/new],
	a.firstname as [firstname/old],
	b.firstname as [firstname/new],
	a.surname as [surname/old],
	b.surname as [surname/new]
from
	#clientOLD a
	inner join #clientNew b on b.id = a.id
for xml
	path('table'), 
	root('AUDIT'), 
	type    

create Trigger dbo.TestTrigger
   on dbo.YourTableName
   for update, insert, delete
as

DECLARE @xmlvar xml;

SELECT @xmlvar =  isnull((SELECT * FROM deleted FOR XML AUTO), '<DELETED RECORD>');

SELECT @xmlvar =  @xmlvar + isnull((SELECT * FROM inserted FOR XML AUTO), '<INSERTED RECORD>');
 
insert into YourAuditTable values (@xmlvar);