Suraj,
Because in that sample the searchFields is not defined for that source the only field being searched is the ownername1 (i.e. the displayfield). If you add the required searchFields property to the source then you can search on any of those fields. If you make this change to the sample then you can search by OWNERNAME1 or PARCELID or SITEADDRESS. But searching for the exact suggestion template will Not work.
var search = new Search({
sources: [{
featureLayer: new FeatureLayer("https://services.arcgis.com/b6gLrKHqgkQb393u/arcgis/rest/services/TaxParcelQuery/FeatureServer/0", {
outFields: ["*"],
infoTemplate: new InfoTemplate("Parcels", "Owner name: ${OWNERNME1}</br>Parcel ID: ${PARCELID}</br>Site address: ${SITEADDRESS}")
}),
outFields: ["OWNERNME1","PARCELID","SITEADDRESS"],
searchFields:["OWNERNME1","PARCELID","SITEADDRESS"],
displayField: "OWNERNME1",
suggestionTemplate: "${PARCELID}: ${SITEADDRESS}",
name: "Parcels",
placeholder: "example: Shawn Smith",
enableSuggestions: true
}],
map: map
}, "search");