PL/SQL :: Extract Values From String To Variables?

I need to extract values from string to variables as below.

declare
str varchar2(100):='Acknowledgment=1234,Order Requester=5678,Site Contact=9999,Other Contact=1456,Pre=1234,23445,56767';
l_a varchar2(100);
l_or  varchar2(100);
l_s  varchar2(100);
l_ot  varchar2(100);
l_pre  varchar2(100);
Begin
l_a:='1234';
l_or:='5678';
l_s:='9999';
l_ot:='1456';
l_pre:='1234,23445,56767';
end;
/

But here challenge is order of alignment change dynamically. ex as below. 

str varchar2(100):='Order Requester=5678,Acknowledgment=1234,Site Contact=9999,Other Contact=1456,Pre=1234,23445,56767';
str varchar2(100):='Pre=1234,23445,56767,Order Requester=5678,Acknowledgment=1234,Site Contact=9999,Other Contact=1456';

 So how to extract Acknowledgement to l_a,Order requester to l_or ...